The present invention relates to a new and improved construction of a circuit arrangement for a remote control receiver, especially a ripple control receiver.
Remote control receivers which have their input signal delivered thereto in the form of a signal superimposed upon the line voltage, especially ripple control receivers, are required in very large numbers. For reasons of economy it is therefore absolutely indispensable that such receivers, notwithstanding the considerable technological requirements which are placed thereon, can be fabricated extremely priceworthy. For practical reasons it is additionally desired to maintain the volume or size of such receivers as small as possible. For instance, such receivers are used for actuating street lighting and, therefore, they are preferably installed in the lighting fixture, so that small spatial dimensions are especially desired.
Such receivers possess a selective receiver section for the assigned remote control frequency, an evaluation section arranged following the selective receiver section for the remote control commands which, as a general rule, are in coded form, at least one switching element, actuated by this evaluation section as a function of the evaluation result, for switching-on and switching-off a remotely controlled object, for instance a street lamp, a hot water boiler and so forth. Further, the receiver contains a current supply section, for instance a transformer with which there is connected a rectifier and a filter or smoothing capacitor associated therewith for producing the operating voltages and operating currents needed by the individual sections of the receiver.
While in the past there have been provided at the selective receiver section preferably LC-circuits and in the evaluation section electromechanically operating devices, which, for instance, act purely mechanically upon the switching elements provided for carrying out a remote control command, in more recent times there have been increasingly employed purely electronically operating devices for the aforementioned purposes. Significant in this regard are, for instance, the systems disclosed in Swiss Pat. Nos. 554,617 and 554,618.
In the circuit arrangements disclosed in the aforementioned Swiss patents there is provided for the current supply a transformer following which there is connected a full-wave rectifier and a filter capacitor associated therewith. This arrangement allows for a technically faultless operation, but does not constitute the most economical solution because, a power transformer is relatively expensive. Since the primary side of such power transformer is connected with the power mains or power supply network, it must be designed to withstand surge voltages.
In U.S. Pat. No. 3,978,388 (corresponding to Swiss Pat. No. 567,344) there are described current supply arrangements dispensing with the use of a power transformer. These solutions thus fulfill the requirement of increased economy. Moreover, in U.S. Pat. No. 3,916,211 (corresponding to Swiss Pat. No. 567,824), there is disclosed a circuit arrangement for an electronic remote control receiver which is characterized by the features that a remotely controlled switching element has associated therewith a switching energy storage, with the result that, among other things, there is realized the advantage that the current supply arrangement can be designed even more economically.
Since, on the one hand, with such remote control receiver, currents at the network frequency and harmonic currents of the network frequency and, on the other hand, currents at the frequency of remote control signals appearing on the power line and disturbance signals flow through common current paths containing circuit elements having non-linear characteristic, such as for instance diodes, push-pull or full-wave rectifiers and diode rectifiers as well as Zener diodes and so forth, the possibility exists of mutually mixing or frequency transforming the different frequencies which are present. This has the result that, depending upon the prevailing conditions, there appears a more or less large spectrum of undesired new frequencies. Again, depending upon the given conditions there can be present disturbance frequencies of an intensity which no longer can be neglected.
Owing to the aforementioned mixing and transformation effect the danger exists that the remote control receiver no longer will only respond to the remote control frequency assigned to it, rather -- although indeed with lesser sensitivity -- also to other frequencies which have been promoted by the aforementioned mixing effect. Thus, the response characteristics of the remote control receiver becomes ambiguous.